 
 (defn histogram [xscale density-yscale height margin]
   (let [day-totals (subscribe [:day-totals])]
-    [:g
+    [:g {:style {:fill    "#DA7C30"
+                 :opacity "0.8"}}
      (doall
       (for [[d freq] @day-totals]
         (let [hours  (* freq 0.75)

      (when @totals
        [:g
         [:g {:style {:fill :none
                      :stroke "black"
                      :stroke-width "3"
                      :opacity "0.5"}}
          (c2.svg/line
           (map
            (fn [[day total]]

           {:x      (xscale d)
            :y      scaled
            :height (- height scaled margin)
            :width  1}])))]))

(defn matrix [xscale yscale]
  (let [pings (subscribe [:pings])]
